The "finger walker" is a fascinatingly complex device remotely operated to cling to the overhead tube sheet of a nuclear boiler. Personnel, operating the finger walker from a safe distance outside the boiler shell, "walk" the support structure over the surface of the tube sheet to enable inspection equipment mounted on the structure to ferret out suspicious tubes. Locating defective tubes, remotely operated structure on the finger walker inserts plugs into the tubes where they are welded to block the defective tube from service. This unique technological house pet is disclosed in at least Leshem U.S. Pat. No. 4,018,344 issued Apr. 19, 1977. As evidence of continuing additions and improvements to this structure, reference is made to Savor and Harrison U.S. Pat. No. 4,193,735 issued Mar. 18, 1980.
Although the finger walker clings bat-like to the overhead tube sheets of nuclear boilers, they do not originally fly up to their perch without assistance. It has been common practice for strong young men to squeeze into the boiler shell through an access manway and manually roust the device upward into its initial position. Of course, the strong young men have been subjected to some measure of radiation while within the boiler shell. Naturally, it is desirable to reduce, if not completely obviate, the exposure time of the bodies of this personnel to this hostile environment and thereby protect them from at least the possibility of genetic malformations.
It is highly desirable that the finger walker, and any other equipment terminating its travel in a hostile environment, be mechanically levered into position. Also, it is desirable that such equipment, functioning within the hostile environment, be removed by mechanical arms safely operated by personnel outside in a benign environment.